Figure 3c. Location of artificial target in secondary experiment. (a) Front view of 3D target. The polyhedron has a central triangular section with a base of 2 cm and a height of 1.2 cm (display dimensions), and the smaller triangles linearly interpolate to zero in 20 sections on either side of the central triangle. (b) Side view of 3D target (showing every other section). (c, d) Images from abdominal CT angiography data set show target (white triangle in c, red triangle in d) embedded near center of images.